Power driven hole cutter



Oct. 2, 1962 E. M. CALKINS 3,056,203

POWER DRIVEN HOLE CUTTER Filed March 8, 1960 Q 25 .Zzzzazztor Eugene M (a/A7775 3,856,233 POWER DRIVEN l-IQLE CUTTER Eugene Moses Calirins, 8119 Knowles Lane, El Paso, Tex. Filed Mar. 8, 1960, Ser. No. 13,576 6 (Ilaims. (Cl. 319-360) The present invention relates to improvements in mechanisms for cutting holes in metal plates and particularly relates to a connector for operatively securing a threaded hole cutter to a power driven wrench handle.

The present invention contemplates providing a mechanism for driving a threaded hole cutter of the type for cutting circular or rectangular holes in sheet metal. These hole cutters are provided with a die through which extends a threaded bolt to threadingly receive a punch. A preliminary hole is drilled in the sheet metal and the die is positioned on one surface of the metal with the bolt extending through the preliminary hole and the punch is threaded to the bolt on the other side of the metal. Rotation of the bolt will draw the punch up through the metal into the die to sever the sheet metal and form an opening therethrough of the size of the punch and die.

Cutters of this type are conventionally used in various trades such as for forming holes in electrical boxes and similar locations. It is usually necessary for the operator to assemble the parts of the cutter and when the punch is drawn up against the sheet metal hold the electrical box or the punch or the die against rotation while wrenching the bolt until the cutter is drawn into the die. This is time consuming and requires the extra holding effort with installations frequently making this difiicult and being so located that holding may be impossible.

It is accordingly an object of the present invention to provide a power driven hole cutter which is rapid in operation and which eliminates the need for holding the metal sheet on the metal box being cut.

Another object of the invention is to provide an improved connector in the form of a torque bar which can be simply carried by a tradesman and which permits rapid connection of a cutter to a power driven wrench.

Other objects and advantages will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the referred embodiment thereof in the specification, claims and drawings, in which:

FIGURE 1 is a side elevational view of a power driven cutter assembly constructed in accordance with the principles of the present invention;

FIGURE 2 is an enlarged detailed fragmentary view of the assembly of FIGURE 1 with parts broken away to illustrate details of construction;

FIGURE 3 is a top plan view of a connector torque bar constructed in accordance with the principles of the present invention; and

FIGURE 4 is a vertical sectional view taken substantially along line IVIV of FIGURE 2.

As shown on the drawings:

As illustrated in FIGURE 1 the hole cutter is power driven by a powered wrench handle 10. The handle is formed of an elongated frame with a hand grip or gripping portion 14 at one end that provides a housing for an electrically driven motor controlled by a switch 15. The motor drives a shaft extending through a hollow tubular shank 13 with the shaft driving a rotor 17 rotatably mounted in the Wrench handle head 16.

The rotor 17 is illustrated as provided with a square stud 18 on one face of the head and a socket 19 on the other face of the head. The socket is rectangular in shape so as to receive the head of a bolt 20 of a cutter 21. As will be appreciated, the arrangement illustrated is advantageous in that it permits the cutter 21 to be mounted close to the wrench handle 10 although in some circumstances it may nited States Patent 3,056,203 Patented Oct. 2, 1952 be desirous to use the wrench handle 10 in a position with the stud 18 extending downwardly and fitted with a socket which then receives the head of the bolt .20.

The cutter 21 is connected to the wrench handle for operation, by a torque bar 22.

The torque bar is constructed so that the tradesman may easily disconnect the bar from the power driven Wrench handle 10 and keep the bar 22 and the cutter 21 available in a tool kit so that the wrench handle may be used for other purposes when not being used to drive the cutter. The power driven electrically operated wrench handle is controlled by a switch 15 on the hand grip 14 and while the wrench handle may take various forms it is preferably of the type disclosed in my copending application for patent entitled, Power Socket Wrench, filed March 1, 1960, Serial No. 12,181.

The cutter 21 is provided with a die member 23 having a die opening 24 therein into which is drawn a punch 25. The punch is threaded to the lower end of the bolt 20 after the bolt is inserted into a previously drilled opening 27 in a sheet metal member such as an electrical box 26.

After the die 23, bolt 20, and punch 25 are assembled it is normally necessary to hold the box 26 against rotation while the bolt is rotated by a wrench. With the present structure this is unnecessary and the cutter is connected to the power driven Wrench by the torque bar 22 which connects it to the power driven wrench and holds it against rotation. The friction between the die 23 and the box 26 will prevent rotation of the box. An operator of course grips the hand grip 14 of the wrench handle preventing rotation of the whole unit.

The torque bar 22 in a preferred form incorporates a flat elongated bar 28 with pins 29 and 30 extending from one end of the bar in an axial direction with respect to the cutter. The pins extend into pin receiving openings in the die 23 to lock it against relative rotation with respect to the bar 28 and may be permanently fixed to the cutter or may be removably inserted therein.

The bar 28 has an axially extending opening 31 therethrough for accommodating the bolt 20 and an annular boss 32 projects upwardly around the opening for supporting the head of the bolt 20.

Extending axially upwardly beside the opening 31 are r a pair of magnet lugs 33 and 34. These lugs releasably attach the bar 28 to the head 16 of the wrench handle and hold the bar on the cutter axially against the wrench head and hold the wrench head down against the cutter while it is being driven.

To prevent rotation of the cutter and of the bar 28, it is provided at its free end with a pair of upstanding fingers 35 and 36 defining a recess 37 therebetween for receiving the shank 13 of the wrench handle. The recess prevents relative rotation of the torque bar 22 but permits the handle to be easily separated therefrom by merely lifting upwardly on the handle and breaking the magnet connection between the head 16 and the lugs 33 and 34.

In operation the operator projects the bolt 21) of the cutter through the hole 27 in the sheet metal box 26 and turns the punch 25 up into place. The power driven wrench handle 10 may then be set in place or may previously have been set in place. When the motor is turned on by operating the switch 15 the cutter will rapidly be drawn through the sheet metal to form the hole. The operator need only support the handle of the power driven wrench and need hold no other parts against rotation.

Thus it will be seen that I have provided a power driven hole cutting assembly which meets the objectives and advantages hereinbefore set forth. The apparatus facilitates cutting holes in locations where access heretofore was difiicult or impossible. Furthermore, the device greatly increases the speed of cutting and reduces the manual efiort required. The mechanism is relatively inexpensive to construct and the parts are capable of quick and easy assembly or disassembly.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by the invention.

I claim as my invention:

1. A power hole cutting assembly comprising an elongated wrench handle, a motor on one end of said handle, a driving connector at the other end of said handle connected to be driven by the motor, a threaded hole cutter bolt releasably connected to said driving connector, a torque bar extending substantially parallel to the wrench handle and having an opening therethrough accommodating said bolt, a magnet on the upper side of the torque bar facing said wrench handle for releasably attaching the bar to the handle, means defining a recess on one end or" the torque bar receiving said wrench handle for non-rotatably locking the bar to the handle, a die member non-rotatably locked to said bar, and a punch threaded to said bolt so that the motor driven connector will draw said punch into said die without requiring the provision of extrinsic nonrotational holding means for the die.

2. A connector for operatively securing a power driven wrench handle to a hole cutter having a shouldered threaded member connected to a punch, and a die for receiving the punch comprising a torque bar member, means defining an opening through said torque member so that the threaded member of the hole cutter can project therethrough to thread into the punch, an annular supporting surface surrounding the opening at the upper side of the torque member for supporting the shoulder of the threaded member with the punch and die on the lower side of the torque member, means below said torque member for locking the member to the die, means on upper side of said torque member for holding the torque member on to the handle in an axial direction with respect to the axis of the threaded member, and non-yielding rigid means on the torque member spaced radially from said opening for nonrotatably locking the member to the power driven wrench handle.

3. A connector for operatively securing a power driven wrench handle to a hole cutter having a shouldered threaded member connected to a punch, and a die for receiving the punch comprising a torque bar, an upwardly facing rotation preventing open recess on one end of the bar having a shoulder for engaging the side of the handle of the power driven wrench, a downwardly facing locking means on the other end of the bar for non-rotatably lockingly connecting the bar to the die of the hole cutter positioned below the bar, an upwardly facing magnetic means on said other end of the bar for releasably attaching the bar to the power driven wrench handle positioned above the bar, and means defining an opening through the bar at said other end with an upwardly facing surface surrounding the opening for receiving the shoulder of the threaded member so that the threaded member projects through the opening.

4. A connector for operatively securing a power driven wrench handle having a rotatable drive to a hole cutter having a threaded member connected to a punch, and a die for receiving the punch comprising a torque bar, locking means on the bar for non-rotatably locking one end of the bar to the wrench handle, a pin on the bar positioned to project toward the die when the bar is in an operating position relative to the die to be received by a recess on the die of the hole cutter at the other end of the bar, and means accommodating the threaded member and axially supporting the threaded member so that the drive can drive the threaded member in rotation for drawing the punch into the die.

5. In combination, a hole cutter having an anvil die, a punch for coacting with the die, a bolt for drawing the punch into the die, a stationary handle supporting a rotary drive having a driving connection drivingly connected to the bolt, a bar member having means releasably lockingly non-rotatably connected to the die to prevent rotation thereof, and means releasably non-rotatably connecting the bar to the handle so that the drive will rotate the bolt and the bar member will hold the die non-rotatably while the punch is drawn into the die.

6. In combination, for use with a rotary hole cutter having an anvil die, a punch for coacting with the die, and a bolt for drawing the punch into the die, a mechanism for connecting to the hole cutter comprising a bar member having means for releasably and lockingly non-rotatably connecting to the die, a drive member having a rotatable driving connection for attaching to the bolt and having a stationary handle, and means for non-rotatably lockingly and releasably connecting the handle to the bar member.

References Cited in the file of this patent UNITED STATES PATENTS 291,012 Kern et al. Dec. 25, 1883 1,343,667 Evensen June 15, 1920 1,754,568 Nischan Apr. 15, 1930 2,222,064 Benner Nov. 19, 1940 2,735,489 Fowler Feb. 21, 1956 2,795,158 Croll June 11, 1957 

